Disclosed are methods, compositions, reagents, systems, and kits to prepare and utilize branched multi-functional macromonomers, which contain a ring-opening metathesis polymerizable norbornene group, one or more reactive sites capable of undergoing click chemistry, and a terminal acyl group capable of undergoing a coupling reaction; branched multi-cargo macromonomers; and the corresponding polymers are disclosed herein. Various embodiments show that the macromonomers and polymers disclosed herein display unprecedented control of cargo loading of agents. These materials have the potential to be utilized for the treatment of diseases and conditions such as cancer and hypertension.